A. Field of the Invention
The present invention relates generally to the field of truck maintenance, and more particularly to tool kits for servicing front axles of MACK.RTM. trucks.
B. Description of the Prior Art
In a conventional steering knuckle assembly at the front axle of a MACK.RTM. truck, a tapered knuckle pin is adjustably held within a downwardly open bore in the knuckle assembly housing by a thrust bearing, which in turn is secured by a thrust bearing adjusting screw, commonly referred to as a king pin cap. The king pin cap is an externally-threaded cylindrical slug which mates with an internally threaded wall of the bore in the knuckle assembly housing, and is provided with a cruciform recess in its bottom face for receiving a torque-applying tool, whereby the king pin cap may be removed from threaded engagement within the bore during servicing. Since the king pin cap and mating threads of the bore are open downwardly toward road or highway surfaces, they are exposed to water, salt, dirt and other elements which cause oxidation of or otherwise degrade the threaded connection. Consequently, removal of the king pin cap is often very difficult.
Under prior art practice in use for over half a century, an adapter 2 as shown in FIG. 1 was used in combination with a manual torque wrench to remove the king pin cap. The adapter 10 of the prior art includes four separate protrusions 12, 13, 14, and 15 spaced radially from an axis of rotation of the adapter and arranged every 90 degrees about the axis of rotation, whereby two diametrically opposed protrusions 12 and 14 are received within one intersecting leg of the cruciform recess and two diametrically opposed protrusions 13 and 15 are received within the other intersecting leg of the cruciform recess. Adapter 10 also includes a polygon-shaped hub 16 for engaging a torque wrench for manual rotation. Prior art adapters of this type have certain recognized disadvantages. For example, protrusions 12-15 are prone to camming action or "walking" and becoming dislodged from the king pin cap recess. Also, the protrusions are prone to shearing and can cause damage to the king pin cap recess. These disadvantages are particularly evident when a high level of torque is required to remove the king pin cap, a situation which calls for a long torque wrench. For this reason, service personal have heretofore been instructed not to use a high-torque pneumatic impact gun to drive adapters of this type.
Also under prior art practice, a machine tool tap is commonly used to clear and restore the internal threads of the bore, however such taps are not adapted for use with manual torque means found in a truck servicing garage.